Navigation systems that can generate and display geographic map images are now available. Typically a navigation system that displays map images includes a computer or processor that has stored within its associated memory system, such as in secondary storage, data corresponding to the map images, or data from which the map images may be derived. The map image data, if stored as bit maps, may be retrieved and essentially directly displayed. The map image data may also be stored in another form, such as vector graphic data, from which the computer system may generate a map image.
One increasingly popular use of such navigation systems is for installation in mobile vehicles such as automobiles. Such navigation systems are then provided with a position sensing device, so that the appropriate map image can be selected based on the position of the automobile, so that the position of the automobile may be displayed on the map.
One drawback of common navigation systems is the poor quality of the map images they display. In systems that generate map images from data such as vector graphics data, the detail of the map image is generally sparse. Only objects that are specifically recorded in the data are displayed. While highly detailed vector graphics images are achievable, substantial processing power is required to generate detailed images with the necessary speed, particularly for real-time display of position-dependent map images, requiring expensive and/or specialized processors and/or taking processor time away from other functions that the navigation system might otherwise perform. On the other hand, systems that store detailed map images as bit maps do not store the images in a uniform format. Without a uniform format, the bit mapped images have varying size and distortion factors, making it difficult to accurately determine and display a given location on the map image. The varying size also leaves gaps on the screen as one image is replaced by another. Bit-mapped images also tend not to scale well, providing poor image quality at extremes of viewing scale.
Another drawback of common navigation systems is lack of portability. Navigation systems generally are installed in vehicles such as automobiles. The system cannot be easily removed and placed in another vehicle or carried to another location, and generally do not provide a self-contained power supply for stand-alone operation.
Another problem faced by navigation systems is that of providing a desired level of detailed information in straightforward, easily comprehensible format. Overly crowded graphics images that include too much information can be confusing to the user of the navigation system.
Another problem faced by navigation systems is that of providing a convenient and useful method of moving around the map independently of tracking the position of the navigation system. A simple method of moving to desired portions of a map is needed.
Another problem faced by navigation systems is cost. A navigation system with good performance at reasonable cost is desirable.
A problem faced generally by navigation systems used in aeronautics is that while such information as flight paths, approach vectors, beacon locations and the like may easily be represented in vector graphics, the vector graphics engines used for such displays cannot easily represent the high level of detail and wealth of information provided by an aeronautical chart.
An object of the invention, therefore, is to provide a navigation system displaying improved aeronautical and other map images stored in a unique format, and providing useful information to the user in a straightforward, easily comprehensible format, with easy methods of moving around within the map images, all at reasonable cost such that both a portable navigation system and a vehicle-installed navigation system becomes practical. These and other objects of the invention will become more apparent from the following detailed description of the preferred embodiment.